| abstract |
The present invention relates to a method for calibrating an additive feed to an exhaust gas stream (303) generated by combustion in an internal combustion engine (101). The first post-treatment component 310 is arranged to oxidize nitrogen monoxide NO to nitrogen dioxide (NO 2 ), and a reduction catalytic converter 332 disposed downstream of the first post- . An additive is supplied to the exhaust gas stream 303 for reduction of nitrogen oxides NO x in the reduction catalytic converter 332 and the additive is added to the nitrogen oxides NO x in the exhaust gas stream 303, , And the ratio is corrected. The method further comprises: - removing the NO x from the exhaust gas stream (303) upstream of the first post-treatment component (310) to reduce oxidation of nitrogen monoxide (NO) to nitrogen dioxide (NO 2 ) Feeding the unburned fuel to the exhaust gas stream 303, and correcting the additive supply to the exhaust gas stream 303 when supplying the unburned fuel to the exhaust gas stream 303. |